Control valve of a camshaft adjuster

ABSTRACT

A control valve ( 1 ) of a camshaft adjuster is provided having a multi-part housing ( 2 ) that is formed as a screw

FIELD OF THE INVENTION

The invention relates to a control valve of a camshaft adjuster.

BACKGROUND

Camshaft adjusters are used in internal combustion engines to vary the control times of combustion chamber valves, in order to be able to vary the phase relationship between a crankshaft and a camshaft in a defined angular range between a maximum advanced position and a maximum retarded position. The adaptation of the control times to the current load and engine speed reduces fuel consumption and emissions. For this purpose, camshaft adjusters are integrated into a drive train by which a torque is transferred from the crankshaft to the camshaft. This drive train can be formed, for example, as a belt, chain, or gearwheel drive.

For a hydraulic camshaft adjuster, the driven element and the drive element form one or more pairs of pressure chambers that act against each other and can be loaded with hydraulic medium. The drive element and the driven element are arranged coaxially. By filling and emptying individual pressure chambers, a relative movement is generated between the drive element and the driven element. A spring with a rotating action between the drive element and the driven element forces the drive element opposite the driven element in a preferred direction. This preferred direction can be in the same direction or opposite direction relative to the rotational direction.

One construction of the hydraulic camshaft adjuster is the vane cell adjuster. The vane cell adjuster has a stator, a rotor, and a drive wheel with an outer toothed section. The rotor is formed as a driven element usually so that it can be locked in rotation with the camshaft. The drive element includes the stator and the drive wheel. The stator and the drive wheel are locked in rotation with each other or alternatively formed integrally with each other. The rotor is arranged coaxial to the stator and within the stator. With their radially extending vanes, the rotor and the stator form oil chambers that act opposite each other and can be loaded by oil pressure and allow a relative rotation between the stator and the rotor. The vanes are formed either integrally with the rotor or the stator or arranged as “inserted vanes” in grooves of the rotor or stator provided for this purpose. Furthermore, the vane cell adjusters have various sealing covers. The stator and the sealing covers are secured with each other by means of several screw connections.

A different construction of the hydraulic camshaft adjuster is the axial piston adjuster. Here, a displacement element is shifted axially by means of oil pressure and this displacement element generates a relative rotation between a drive element and a driven element by means of helical toothed sections.

The control valves of the hydraulic camshaft adjusters control the hydraulic medium flow between the camshaft adjuster and the oil pump or the oil reservoir (tank).

The control valve has a hollow cylindrical housing and a rotationally symmetric control piston. The control piston is within the housing of the control valve. The control piston can move in the axial direction and is guided by the housing. Thus, the control piston can be positioned in an arbitrary axial position relative to the housing. The positioning is realized by an electromagnet that contacts an end of the control piston with its actuation pin and can shift the control piston. A spring ensures contact between the control piston and the actuation pin. Through the axial positioning of the control piston, the different connections of the control valve are connected to each other hydraulically or separated from each other and can communicate with each other or not. For guiding the hydraulic medium between the connections, the control piston and housing are provided with openings, e.g., grooves and/or holes. The control piston has control edges that control the flow together with the edges of the openings of the housing. The control edges themselves are the edges of the respective openings, e.g., grooves, of the control piston. For controlling the flow, the edges of the openings of the housing and the control edges are positioned relative to each other, so that an opening of the housing lies opposite an opening of the control piston as much as possible and forms a variable flow surface for the hydraulic medium by means of being able to position the control piston in the axial direction.

A control valve formed as a central valve is arranged coaxial to the axis of symmetry or rotation of the camshaft adjuster or the camshaft. In addition, the central valve is placed within the camshaft adjuster, i.e., central valve and camshaft adjuster are arranged one on top of the other in the radial direction. Optionally, the camshaft can be arranged between the camshaft adjuster and the central valve. The housing of the central valve can be formed as a central screw, wherein the camshaft adjuster is locked in rotation with the camshaft. The electromagnet is arranged as a central magnet aligned as much as possible with the central valve and arranged usually fixed on the frame, especially on the cylinder head.

Alternatively, a control valve with an electromagnet arranged rigidly on the valve can be arranged on an arbitrary position in the hydraulic medium gallery, outside of the camshaft adjuster and the camshaft, and can control the hydraulic medium flow.

SUMMARY

The object of the invention is to provide a control valve of a camshaft adjuster that permits a more economical production.

This object is met by a control valve of a camshaft adjuster, wherein the control valve for controlling the camshaft adjuster carries a flow of hydraulic medium and the control valve has a supply connection, multiple work connections, and a tank connection, wherein the control valve has a housing formed as a screw with a cylindrical hollow space in which a control piston is guided so that it can move in the axial direction, wherein the housing formed as a screw is formed in multiple parts and has a threaded body and a sleeve, wherein the threaded body is connected to the sleeve arranged peripheral to the threaded body.

The housing has several openings and a control piston that can move in the axial direction in the cylindrical hollow space of the housing, wherein a control edge of the control piston can be positioned in the axial direction relative to an opening of the housing for controlling the hydraulic medium flow between the supply connection, the work connections, and the tank connection, in order to change the flow path for the hydraulic medium flow between the connections through the opening.

The control valve is preferably formed as a central valve and thus the housing as a central screw, by which the camshaft adjuster is locked in rotation with the camshaft.

Through the invention it is advantageously achieved that different threaded bodies can be combined with a sleeve or different sleeves with a threaded body. Another advantage is that the production and heat treatment can be individually adapted to both components. In addition, different materials can be used for the threaded body and for the sleeve.

Different threaded bodies can vary in length, thread pitch, and thread type and can be adapted to an individual receptacle, e.g., of the camshaft, provided for this purpose. The threaded body is advantageously formed as a threaded bar and has a thread section, an elongation section, and a positive locking section. The thread section is provided for anchoring, e.g., to a camshaft. The elongation section is formed for providing the elasticity necessary for the thread connection. The positive locking section is formed for the positive locking attachment to the sleeve. As an alternative to the positive locking section, a non-positive locking section or a material locking section could also be provided for the non-positive or material locking and rotationally fixed attachment to the sleeve.

Different sleeves can vary in length, diameter, and production quality and can be adapted to an individual receptacle, e.g., the hub of the camshaft adjuster, provided for this purpose.

The sleeve can have, on one of its ends, an attachment body for a mounting tool, preferably for mounting the camshaft adjuster with the camshaft. The attachment body is advantageously formed as a hexagon analogous to a hexagonal screw head. Alternative screw body shapes can be formed instead of the hexagon screw head.

In one advantageous construction of the invention, the threaded body has a positive locking element that is held in a complementary receptacle of the sleeve, wherein, by means of the positive locking, a connection is formed between the sleeve and the threaded body. The positive locking fixes the sleeve relative to the threaded body at least in the axial direction. The complementary receptacle can be arranged preferably in the base of the sleeve or on an inner periphery or outer periphery of the sleeve.

Preferably the positive locking element also has surfaces on a circumferential face that match surfaces of the complementary receptacle of the sleeve such that a torque can be transferred between both components. In this way, as mentioned above, an attachment body is formed for an installation tool of the sleeve.

Alternatively, the positive locking between the sleeve and threaded body cannot transmit sufficient torque for fastening the camshaft adjuster to the camshaft. For example, the sleeve and threaded body are fixed axially and/or radially to each other, but the positive locking allows rotation between the sleeve and threaded body. In this case, the threaded body has an attachment body for an installation tool. The attachment body is advantageously formed as a hexagon analogous to a hexagonal screw. Alternative screw head shapes can be formed instead of the hexagonal screw head. This rotational capability can be formed completely without resistance, that is, with play, or can be formed without play at least up to a certain torque that, however, is not sufficient for fastening of the camshaft adjuster on the camshaft.

In a detailed construction of the invention, the complementary receptacle is arranged inside the sleeve. Preferably the complementary receptacle can be arranged in the interior of the sleeve on a surface turned toward the interior of the sleeve on an inner periphery or the base. Similarly, the sleeve can have a pin that has the complementary receptacle on its inner periphery.

In an alternative detailed construction of the invention, the complementary receptacle is arranged outside the sleeve. Preferably, the complementary receptacle can be arranged in the inside of the sleeve on the surface turned toward the outside of the sleeve on an outer periphery or the base. Similarly, the sleeve can have a pin that has the complementary receptacle for the positive locking element of the threaded body on its outer periphery.

In one preferred construction of the invention, the sleeve has the cylindrical hollow space with a guide surface that guides the control piston so it can move in the axial direction. The guide surface can be formed here by an inner circumferential surface of the sleeve itself or by an inner circumferential surface of an intermediate sleeve.

In another construction of the invention, the sleeve is formed as a deep drawn part or an extruded part. Preferably, these production methods can improve the economical production.

In a preferred construction of the invention, the threaded body is constructed as a formed part. Preferably, this production method can improve the economical production.

In addition to forming, a material-cutting method, preferably turning, can be used to form the final shape of the threaded body. Alternatively, the threaded body can be produced only by a material-cutting method, preferably turning.

In another construction, the threaded body has a central passage opening. Preferably, this passage opening can be formed as a supply connection, work connection, or tank connection of the control valve.

In a very preferred construction of the invention, the threaded body has an external thread that can be brought into engagement with an internal thread of a camshaft. Alternatively, the threaded body has an internal thread that can be brought into engagement with an external thread of a camshaft. Preferably, the thread, either internal thread or external, of the threaded body can be adapted to the thread of the camshaft or different threads of the threaded body can be adapted to different camshafts, without having to change the shape or production technique of the sleeve, preferably with the control piston arranged therein.

In one especially preferred construction of the invention, the sleeve has a screw head on an end side of the sleeve that is formed as a flange. Preferably, both a stop for the camshaft adjuster and also an attachment body for an installation tool are formed on the flange and thus a space-saving arrangement is made. Alternatively, the screw head could be formed on an end side of the threaded body, wherein the sleeve nevertheless has a stop, preferably a flange, for the camshaft adjuster.

Due to the construction according to the invention for the control valve, for one, a more economical production of the control valve is possible and, second, many different configurations of different sleeves with different threaded bodies can be made, primarily, for installation, which enables high flexibility with respect to a wide spectrum of applications.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are shown in the figures.

Shown are:

FIG. 1 a control valve formed as a central valve, and

FIG. 2 a multiple-part housing according to the invention of a control valve formed as a central valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a control valve 1 formed as a central valve.

The control valve 1 has a multiple-part housing 2, a plastic sleeve 15, a guide sleeve 3, a control valve 4, two compression springs 18 and 20, a valve seat plate 21, a ball 19, a control piston 4, a spring support plate 33, and optionally a spacer 22. All of the components named above are arranged coaxial to each other and to a common axis of rotation 34 that is also the axis of rotation 34 of a camshaft adjuster or a camshaft.

The multiple-part housing 2 that is formed as a screw is provided for the rotationally locked attachment of the camshaft adjuster to the camshaft. The multiple-part housing 2 is formed of a sleeve 6 and a threaded body 5. The plastic sleeve 15 is held by an inner circumferential surface of the sleeve 6. The plastic sleeve 15 has channels and openings to guide hydraulic medium from a supply connection P of the control valve 1 to the work connections A and B. The work connections A and B are arranged at different, angle-offset positions as radial holes 24 and 25 of the sleeve 6. The supply connection P is formed by a passage opening 10 in the threaded body 5. The passage opening 10 is formed as a hole coaxial to the rotational axis 34 and passes completely through the threaded body 5. The tank connection is located on the end side 13 of the control valve 1 opposite the supply connection P.

Force is applied to the control piston 4 by the compression spring 18 and this control piston is pressed against the securing ring 17. The securing ring 17 secures the axial position of the plastic sleeve 15 and the control piston 4 inside the sleeve 6. The compression spring 18 is supported, on one side, on the control piston 4 and, on the other side, on the spring support plate 33. The spring support plate 33 is connected rigidly to the plastic sleeve 15, as are also the guide sleeve 16 and the valve seat plate 21. The ball 19 is pressed by the compression spring 20 against the valve seat plate 21. These three components form a non-return valve that permits a flow of hydraulic medium from the supply connection P into the inside of the control valve 1, but prevents a return flow.

The control piston 4 is guided by means of its outer circumference by a guide surface 9 of the guide sleeve 16. The housing 2 or the sleeve 6 has a hole 23 that is closed by the spacer 22. On one hand, the spacer 22 positions the plastic sleeve 15 so that the hydraulic medium can reach from the holes 24 and 25 to the control piston 4. On the other hand, the spacer 22 can also have, in addition to its passage opening arranged coaxial to the rotational axis 34, several radial holes that can optionally lead hydraulic medium from the hole 23 to the control piston 4 and thus can provide the hole 23 as an additional supply connection, work connection, or tank connection.

The control of the hydraulic medium flow between the connections P, T, A, and B is known by those skilled in the art. The control of the hydraulic medium to the work connections A and B, which lead to the work chambers of the camshaft adjuster, is also known from the prior art and generates the relative adjustment between the camshaft and crankshaft. The control piston 4 is shifted according to the prior art by an actuation pin of an electromagnet, in particular, a central magnet, in its axial position, so that the hydraulic medium can be distributed from the supply connection P to the work connections A and B.

The sleeve 6 has a flange 14 on the end side 13 on which the tank connection T is arranged and a perforated base 35 on the end side 30 opposite the end side 13. The inner circumferential surface 36 of the perforated base 35 has a circular shape and is arranged coaxial to the rotational axis 24. This inner circumferential surface 36 is part of the complementary receptacle 8 for the positive locking element 7, wherein this inner circumferential surface 36 contacts an outer circumferential surface 37 of the positive locking section 27 of the threaded body 5 and fixes the threaded body 5 radial to the rotational axis 34. Radial play between the inner circumferential surface 36 and the outer circumferential surface 37 can be provided or not.

In the axial direction along the rotational axis 34 and in the direction of the end side 13, the inner circumferential surface 36 contacts a circular inner surface 40 that is formed as an axial stop for the threaded body 5 for the axial positioning of the threaded body 5 relative to the sleeve 6. The circular inner surface 40 is part of the complementary receptacle 8 for the positive locking element 7 and contacts a circular outer surface 41 of the positive locking section 27 of the threaded body 5.

In addition, the complementary receptacle 8 of the sleeve 6 has another inner circumferential surface 38 that has a larger diameter than the inner circumferential surface 36. In the axial direction along the rotational axis 34 and in the direction of the end side 13, the inner circumferential surface 38 contacts the circular inner surface 40. This inner circumferential surface 38 contacts an outer circumferential surface 39 of the positive locking section 27 of the threaded body 5 and fixes the threaded body 5 in the radial direction relative to the rotational axis 34 with the sleeve 6. Radial play between the inner circumferential surface 38 and the outer circumferential surface 39 can be provided or not.

At a minimum, the positive locking can have a rotationally fixed construction either between the inner circumferential surface 38 and the outer circumferential surface 39 or between the inner circumferential surface 36 and the outer circumferential surface 37.

Alternatively, the inner circumferential surface 38 and the outer circumferential surface 39 and/or the inner circumferential surface 36 and the outer circumferential surface 37 can have a cylindrical shape and each can be provided with or without radial play. If there is no radial play in at least one surface pair, this non-positive locking fit, preferably an interference fit, can form the rotationally locked connection. If radial play is provided in both surface pairs, the rotationally fixed connection can be formed by fusion, adhesion, or welding.

The threaded body 5 is divided into three sections the positive locking section 27, the elongation section 26, and the threaded section 31. The positive locking section 27 has the cylindrical outer circumferential surface 37, the circular ring-shaped outer surface 41, and the cylindrical outer circumferential surface 39. In the direction of the rotational axis 34, the elongation section 26 that has a smaller cross section than the positive locking section 27 or the threaded section 31 contacts the cylindrical outer circumferential surface 39 of the positive locking section 27. The elongation section 26 is constructed in its length and its cross section such that the desired pretensioning force can be realized. Furthermore, in the axial direction along the rotational axis 34, the threaded section 31 that has an external thread for engaging with an internal thread of a camshaft connects with the elongation section 26.

The threaded body 6 is constructed as a formed part. The positive locking section 27 with its surfaces for the complementary receptacle 8, the elongation section 26, and the threaded section 31 are formed by material extrusion. The external thread of the threaded section 31 is rolled. The passage opening 10 can be either drilled or formed by an extrusion method. Cutting methods, e.g., such as turning or grinding, can also be used for forming desired tolerance areas.

Starting from the base 35 passed through by the threaded body 5 and then at the complementary receptacle 8, the sleeve 6 has the cylindrical hollow space 3 in which the previously mentioned components are arranged. On the end side 13 of the sleeve 6 there is a flange 14 that is formed as a radially projecting collar. The flange 14 has an engagement body 32 with a screw head 12 and also a contact surface 28 for contacting a camshaft adjuster. The engagement body 32 has several surfaces that form the screw head 12 on the outer circumference of the flange 14. The arrangement of the surfaces corresponds to an external hexagon. The contact surface 28 is formed as a circular ring-shaped surface and oriented toward the other end side 30.

The sleeve 6 is constructed as a formed part, preferably as a deep drawn or extruded part. The structure of the engagement body 32 of the flange 14 formed as a screw head 12, as well as the cylindrical hollow space 3 and the complementary receptacle 8, can be preferably formed by this method. The hole in the base 35 and also the radial holes 23, 24, 25 can be formed by a punching process. Cutting methods, e.g., turning or grinding, can also be used for forming desired tolerance areas.

Through the rotationally locked connection between the positive locking section 27 of the threaded body 5 and the complementary receptacle 8 of the sleeve 6, a torque is transmitted, starting from an installation tool that acts on the engagement body 32 constructed as screw head 12 to the threaded section 31 of the threaded body 5. In this way, the control valve 1 constructed as a central valve can be used with its multiple-part housing 2 formed as a screw for the rotationally locked connection of a camshaft adjuster to a camshaft.

FIG. 2 shows a multiple-part housing 2 according to the invention in a control valve 1 formed as a central valve. The configuration is similar to the housing 2 from FIG. 1, so only the differences will be discussed below.

The engagement body 32 is constructed by the positive locking section 27 of the threaded body 5. The screw head 12 of the engagement body 32 is here formed as an internal hexagon. The flange 14 has a cylindrical external lateral surface and functionally has only the contact surface 28 that is provided for contacting a camshaft adjuster. In addition, the flange 14 is arranged at a distance from the end surface 13. The elongation section 26 and the threaded section 31 have an external diameter that is uniform as much as possible. The arrangement and the construction of the connections (feed connection, work connection, tank connection) is here disregarded in favor of clearly explaining the invention. The surface pairing of the inner circumferential surface 38 and the outer circumferential surface 39 can be constructed as shown. The inner circumferential surface 38 is constructed as an inner hexagon and the outer circumferential surface 39 is constructed cylindrically. A small amount of play or even no play can be provided in this surface pairing.

The inner circumferential surface 38 formed as an inner hexagon can alternatively be paired to an outer circumferential surface 39 formed as an external hexagon, wherein a rotationally locked connection can be formed between the sleeve 6 and the threaded body 5.

In contrast to the construction of the control valve 1 according to FIG. 1, according to the construction according to FIG. 2 first the multiple-part housing 2 with a camshaft adjuster and a camshaft is installed, whereupon the assembly contacts the component arranged in the cylindrical hollow space. The guide surface 9 of the cylindrical hollow space 3 can be contacted directly by a control piston 4.

List of Reference Numbers 1) Control valve 2) Housing 3) Cylindrical hollow space 4) Control piston 5) Threaded body 6) Sleeve 7) Positive locking element 8) Complementary receptacle 9) Guide surface 10) Passage opening 11) Outer thread 12) Screw head 13) End side 14) Flange 15) Plastic sleeve 16) Guide sleeve 17) Securing ring 18) Compression spring 19) Ball 20) Compression spring 21) Valve seat plate 22) Spacer 23) Hole 24) Hole 25) Hole 26) Elongation section 27) Positive locking section 28) Contact surface 29) Outer circumferential surface 30) End side 31) Threaded section 32) Contact body 33) Spring support plate 34) Axis of rotation 35) Base 36) Inner circumferential surface 37) Outer circumferential surface 38) Inner circumferential surface 39) Outer circumferential surface 40) Inner surface 41) Outer surface A) Work connection B) Work connection P) Supply connection T) Tank connection 

1. A control valve of a camshaft adjuster, that carries a flow of hydraulic medium for controlling the camshaft adjuster, the control valve comprises: a supply connection (P), several work connections (A, B), and a tank connection (T), a housing formed as a screw with a cylindrical hollow space in which a control piston is guided so that it is movable in an axial direction, the housing formed as a screw has a multiple-part construction including a threaded body and a sleeve, and the threaded body is connected to the sleeve which is arranged peripheral to the threaded body.
 2. The control valve according to claim 1, wherein the threaded body has a positive locking element that is held in a complementary receptacle of the sleeve, and a connection between the sleeve and the threaded body is formed by positive locking.
 3. The control valve according to claim 2, wherein the complementary receptacle is arranged inside the sleeve.
 4. The control valve according to claim 2, wherein the complementary receptacle is arranged outside the sleeve.
 5. The control valve according to claim 1, wherein the sleeve includes the cylindrical hollow space having a guide surface that guides the control piston so that it is movable in the axial direction.
 6. The control valve according to claim 1, wherein the sleeve is constructed as a deep-drawn part or extruded part.
 7. The control valve according to claim 1, wherein the threaded body is constructed as a formed part.
 8. The control valve according to claim 1, wherein the threaded body has a central passage opening.
 9. The control valve according to claim 1, wherein the threaded body has an external thread that is engageable with an inner thread of a camshaft.
 10. The control valve according to claim 1, wherein the sleeve has a screw head on an end side of the sleeve that is formed as flange. 